Magnetoresistance of La0.67Sr0.33MnO3 epitaxial films grown on a substrate with low lattice mismatch

The structure, electrical resistivity, and magnetoresistance of La0.67Sr0.33MnO3 heteroepitaxial films (120-nm thick) practically unstrained by lattice mismatch with the substrate were studied. A strong maximum of negative magnetoresistance of approximate to 27% (for mu H-0 = 4 T) was observed at T approximate to 360 K. While the magnetoresistance decreased monotonically in magnitude with decreasing temperature, it was still in excess of 2% at 150 K. For T < 250 K, the temperature dependence of the electrical resistivity rho of La0.67Sr0.33MnO3 films is fitted well by the relation rho = rho(0) + rho(1)(H)T (2.3), where rho(0) = 1.1 x 10(-4) Omega cm, rho(1)(H = 0) = 1.8 x 10(-9) Omega cm/K-2.3, and rho(1)(mu H-0 = 4 T)/rho(1)(H = 0) approximate to 0.96. The temperature dependence of a parameter gamma characterizing the extent to which the electrical resistivity of the ferromagnetic phase of La0.67Sr0.33MnO3 films is suppressed by a magnetic field (mu H-0 = 5 T) was determined. (c) 2005 Pleiades Publishing, Inc.